Method of making impervious bags



Feb. 6, 1940. G. A. MOORE METHOD OF MAKING IMPERVIOUS BAGS Filed May 27,1936 BY mm M ATTORNEY Patented Feb. 6, 1940 UNITED STATES METHOD OFMAKING IMPERVIOUS BAG S George Arlington Moore, Louisville, Ky.,assignor to Humoco Corporation, Louisville, Ky., a corporation ofDelaware Application May 27, 1936, Serial No. 81,981

3 Claims.

This invention relates to containers and more particularly to containerscomprising fibrous materials and to a method and means for sealing thesame.

5 It has been hereto-fore proposed to seal the ends or seamsof'containers made of waxed paper 'by the application of heat andpressure thereto. the wax body being thus rendered eilective to hold theadjacent surfaces of the container together. Joints or seams formed inthis manner. however, are not impervious to air under all conditions;the joints are always weak as surface tension is relied upon, the sealformed thereby is easily broken, thus necessitating very carefulhandling. Said wax joints or seams become particularly weak when thepackage is subjected to merely ordinary room temperatures in hotseasons, thus resulting in the breaking of the package at the joints orseams and loss of the contents thereof.

It has also been proposed to seal packages made of wax impregnatedfibrous materials by applying a solvent activatable adhesive to amarginal unwaxed portion of the open end or joints thereof. 25 Thismethod of sealing not only increases the cost and difllculties involvedin the manufacture of the bag but, in addition, subjects the contents tocontamination during the step of activating said adhesive. Furthermore,it is extremely dirficult, if not impossible, to seal a container inthis manner and render the same impervious to both air and moistureunder all conditions of temperature and humidity. It is also a wellknownfact that fibrous materials such as paper 35 or cardboard are weakenedbodily when soaked with liquid parafiin or the like or when dampenedwith adhesive activating solvents.

It is accordingly an object of this invention to provide a novelsanitary container made at least 40 in part of fibrous materials whichis adapted to be readily sealed and which can be impervious to air andmoisture.

Another object is to provide novel means for simultaneously sealing apackage and forming a 45 line of severance without impairing theimperviousness of the seal whereby the package may be readily opened fordispensing the contents thereof.

Still another object is to provide a novel and sanitary fibrous packageformed from a single blank which is impervious to air and moisture,

and a novel method for making same.

A further object is to provide an impervious package of fibrousmaterials wherein the fibers of the material are not weakened in theprocess of manufacture, such as by impregnating the same with paraflinwax.

Another object is to provide a novel bag or container which can besecurely closed without the use of string, gum tape, etc. 5

The above and further objects and novel features of the invention willmore fully appear from the following detailed description when taken inconnection with the accompanying drawing. It is to be expresslyunderstood, how- 10 ever, that the drawing is for the purpose ofillustration only and is not designed as a definition of the limits ofthe invention, reference being primarily had for this purpose to theappended claims.

In the drawing, wherein like reference characters refer to like partsthroughout the several views,

Fig. 1 is an isometric view of one form of package which may be employedin carrying out the present invention, the same being shown with one endopen;

Fig. 2 is a similar view showing the container after the open end hasbeen sealed;

Fig. 3 is a side elevation of one form of apparatus which may be used toseal the open end of the package of Fig. 1;

Fig. 4 is a front elevation of said apparatus with parts thereof brokenaway; and,

Fig. 5 is an enlarged detail view of the heating irons of the device ofFig. 3.

The single embodiment of the invention illustrated is shown, by way ofexample, as comprising a paper bag ill of the same type and texture aspaper bags commonly employed in grocery stores for packaging bulk foodsor the like. Bag in is preferably constructed of a single sheet or blankor fibrous material such as paper, folded in any suitable or weli-knownmanner to form a container having at least one end thereof open as seenin Fig, 1. In the form shown, the blank is folded so as to form acontainer of rectangular cross-section, the ends of the blank beingbrought into overlapping relation to form a vertical joint or seam ii.The bottom is thereafter formed by folding a marginal portion of theblank in the usual or any suitable or desirable manner. In view or themany common methods in which the paper may be folded to form the bottomof the container, it is believed to be unnecessary to show any specificembodiment.

In order to render bag or package I. impervious to air and moisture forthe purpose of preserving the contents to be sealed therein, the side ofthe blank constituting the inner surface of the bag sealing {30 iscoated with a thin, dry film I2 of a thermoplastic lacquer havingpotential cementing qualities. As an example, said film may be composedof a nitro-cellulose lacquer having thermoplastic qualities, or for somepurposes cellulose acetate may be advantageously employed. The lacqueror acetate film constitutes an impervious coating whichwill increaserather than impair the tensile strength of the fibrous material, and theadhesive qualities thereof may be utilized in the construction andsealing of the container, as will morefully appear hereafter. Lacquerfilm I2 is preferably constituted by a lacquer that may be activated orrendered tacky by a solvent, by heat, or by both, and when heat alone isused as an activating agent said lacquer should be rendered tacky onlyattemperatures considerably in excess of usual room temperatures,- forexample 130 to 150 F.

While lacquer coating or film I2 may be placed on the innner surface ofbag III by means of a spray, for example, after the latter is formed inthe usual or any well-known manner, it is preferable to apply the filmto the surface of the blank before the same is folded to form acontainer of the desired shape. The cementing qualities of the lacquermay thus be utilized in the construction ofthe container to firmly andim- 1 form a strong, impervious bond between the same.

The bond thus formed will not be weakened when the package is subjectedto a wide variation of room temperatures in any season, since thelacquer is affected only by comparatively high temperatures,

One. suitable lacquer which may be employed to form the coating ontheinner surface of container I0 is composed of about 65 percent of estersolvents, such as ethyl acetate, butyl acetate or the like, and suchhydro-carbon as toluol, and about 35 percent of solids which. can bereadily activated by solvents as well as heat. The solids content iscomposed of about 25 percent of low viscosity nitro-cotton, 60 percentof resins and about 15 percent of a plasticizer such as dibutylphthalate. The resins employed may contain some gums, such as ester gum,but usually synthetic resins which have more definite physicalproperties than any natural resin are used. This lacquer is free fromtack at room temperatures 'and under normal conditions of humidity.Contact temperatures for forming seals at the overlapped portions of theblank from which container I 0 is constructed must be in excess of F.,the excess being dependent upon the speed of operation and theconductivity of the materials used. The above lacquer is also adapted toharden quickly after activation and accordingly permits rapid operationof the sealing machinery.

It has'been the practice heretofore, particularly in grocery stores andsimilar places of business, to fill uncoated paper packages or bagssimilar to the above and tie the same with cord or employ a separateadhesivecoated strip to hold the closing foldsof the open end in place.Much time is unnecessarily consumed in closing bags in this manner andthe resulting closure Heat and pressure may be apis not impervious toair and moisture and is subject to leakage. With the novel bagconstructed in the manner above described, the open end thereof may bereadily and quickly closed and bonded by an impervious seal after thedesired contents have been placed therein. The grocer or other merchantis thus enabled to package bulk foods and those which are apt todeteriorate when subjected to atmospheric conditions of temperature andhumidity in an inexpensive, impervious package. Such articles, eventhough hygroscopic, may thus be packaged and retained on the shelves forsale during an indefinite period without danger of deterioration.

In the embodiment of the invention illustrated narrow strips I3 at theupper margins of two opposed sides Illa, Illa of the container are alsocoated with a thin, dry film of thermoplastic lacquer of the characterabove described. The

'open end of the container may thusbe sealed-by merely pressing orfolding the sides .Illa, lIla of container Ill inwardly, as indicated bydotted lines in Fig. 2, thereby causing opposite endsof strips I3 toengage one another, and simultaneously pressing the inner coatedsurfaces of the marginal edges of sides IIlb, IIlb, into engagement witheach other in a manner which will be readily apparent from an inspectionof the drawing.

It will be noted that in folding the upper margins of sides Illa, Illaalong the folding lines or creases a, b,which may be provided ifdesired, the edges of said sides drop below the upper edges of sidesIUb, Illb. It will of course be understood that the thickness of thematerial from which the bag I0 is fabricated is exaggerated in thedrawing for the purpose of clarity. Heat and pressure sufiicient toactivate film I2, I3 are then simultaneously applied to the outersurfaces of the marginal portions of sides lIlb to complete the seal,the heat activated adhesive being pressed into the interstices of thepaper to form an impervious bond. With the sides Iflb entirely coatedwith thermoplastic lacquer, the closure seal may be made at any pointthroughout the length of the bag in case the latter'is not completelyfilled.

Novel portable apparatus suitable for use on the counter in a retailstore is provided for forming the closure seal above described and forsimultaneously. producing indentations and corriplementary ridgesconstituting a line of severance adjacent said seam without impairingthe impervious character thereof whereby the package may be readily andneatly opened for dispensing the contents thereof. In the illustratedform, said apparatus comprises a stand I4 having a pair of axiallyspaced trunnions I5, I5 in which a shaft I6 is rotatably journaled.Keyed or otherwise suitably secured to said shaft between trunnions I5is a handle I1. A U-shaped pressure and heating member comprising a pairof arms I8, l8 having hub portions keyed to shaft l6 and a heating andpressing iron I9 joining the lower ends of said arms is adapted to bepivotally moved by handle I! so that the inner surface of said iron willmove into parallel relationship and cooperate with the fiat face of aniron 20 which is secured to a portion 22 mounted on stand I4 directlybelow trunnions I5.

Any suitable means may be provided for heating members I9 and 20 .todesired temperatures,

I such means as shown being constituted by elecscribed.

'ruptedlineacrossthe faceofsealingiron amass:

iacent member 2l.- Ilements ll may be connected to any suitable sourceof electric current through leads II.

In order that the bag may be readily opened after being sealed by theapparatus above dea plurality of 'wedge shaped beads 24 may be providedin a horizontal inter- II edge thereof and a plurality (Fig.

adiacent the lower Thus, when the upper endof the bag ll, after the sameis folded in the manner illustrated and above described, is held betweenparts II and II and pressure is applied by pressing downwardly on theouter end of handle ll, films I! and I! will be activated at the pointsof heat application, 1. e., throughout the width of the container, andpressed into the interstices of the paper to form an impervious bondbetween the engaging surfaces. At the same time, through the cooperationof beads 24 and grooves 25, a line of indentations I! (Fig. 2) isproduced adjacent the lower edge of the seam, thereby forming a line ofseverance whereby the container may be readily opened. Since thepressure applied by beads 23 on one side of the seal isrelieved bygrooves 24 on the opposite side, it will be seen that the paper will notbe ruptured nor the impervious character of the package impaired.

Any suitable means, such as coil springs 11, interposed between stand isand arms it, may be provided for normally holding the faces of sealingirons I. and II out of engagement. If desired, suitable cutting meansmay be provided adjacent the upper edges of members is and II fortrimming any excess paper from the top of the container simultaneouslywith the making 01' the closure seam.

There is thus provided a novel, fibrous bag or package which may bereadily and inexpensively manufactured and anovel method and means forconstructing the same and sealing a commodity therein, whereby thelatter will notonlybe protected from air and moisture outside the bagbut will retain the moisture which is in the contents at the time ofpacking. A neat appearing package which may be readily opened is alsothus provided.

Although only a single embodiment of the invention is illustrated andducribed in detail, expressly understood that the same not limitedthereto but that various changes in the design and arrangement ofasinthesiaeand shapecfthe without departing from the spirit invention,as will now be apttothoaelkilledin theart. Incertainin- .gss

Incarryingoutthemethodof present invention, it mayproveusefultocontainer.

- 3 employ a solvent in addition to heat for cementing the vertical seamand bottom folds. The top seam, however, is preferably made by theapplication of heat only. The thermoplastic lac-. quer characteristicssuch that the bags, prior to use, may be stored for long periods of timewithout any danger of the lacquer becoming tacky or that temperaturechanges will cause the parts to adhere one to the other, whereby theusefulness of the bags would be destroyed, as would be the case ifcommon adhesives, such as animal or vegetable glue, were used to sealthe bag. For a definition of the limits of the invention, reference willbe had primarily to the appended claims.

What is claimed is:

l. The method of forming end-closure on a container having a mouth atone end thereof U which consists in tucking the ends of said mouthinwardly and drawing the inner surface of the sides of said mouth intocontact with each other and with the inner surfaces of the tucked endsof said mouth, applying heat and pressure to activate a lacquer coatingon said engaging surfaces to cement said surfaces together and form animpervious seal across said mouth, and si-' multaneously impressing aplurality of aligned indentations in said sealed portion across thewidth of said container to provide a line of severance whereby thecontainer may be readily opened.

2. The method of closing an open ended concoating the inner surfacetainer which includes of the margin and two oppositely disposed portionsof the outer surface of the margin at the open end of the container witha thin, dry film of thermoplastic lacquer having potential adhe-. sivequalities, tucking the double coated portions of the margin inwardly andsimultaneously drawing the single coated portions of the margin intocontact, applying heat and pressure to the engaging surfaces to activatesaid coating for adhesively securing said eng ing surfaces together toform an impervious seal across said open end, and impressing a pluralityof indentations and complementary ribs across the width of said.container to provide a line of severance whereby the same may bereadily o 3. The method of forming an end closure on a paper containerformed of flexible sheet material which consists in tucking the ends ofthe mouth of said container inwardly to thereby flatten the end of thecontainer, applying heat and pressure to the margin of the flattened endto activate a dry coating of thermoplastic lacquer on the engagingsurfaces of said margin to adhesively secure said surfaces together andform an impervious seal across said mouth, and simultaneously impressinga plurality of aligned indentations and complementary ribs in said sealto provide a line of severance for opening the GEORGE ARLINGTON MOORE.

